What can you cut with a 300mW DIY laser cutter?

I built this laser cutter after being inspired by this laser cutter and the design is almos identical, there for I will not go into details about my build but will instead focus on what you can do with it.

Since the diode (LPC-826) I have used is from a DVD burner and have an output power of 300-400 mW, it can’t be considered very powerful when it comes to cutting lasers. It should not be confused with a CO2 laser which have an output power of 50W, which is the type of laser that is normally is used in professional laser cutters.

The materials I have tried so far are:

Adhesive plastic (stickers) – Cuts right through

Art Foam/EVA foam – Cuts right through

Wood – It burns the wood but does not cut. Can be used for engraving.

Paper – Black copy paper can easily be cut but thicker paper does not work. White paper does not work.

ABS Plastic – The surface melts so it is possible to engrave but it can’t be cut.

Plexiglass – Not a mark.

Plasticard – The thinnest sheet I tried could be cut at low speed but only after having been painted black.

Adhesive plastic

This is what I find by far the most useful application for this laser cutter. So far it has been able to cut through any type and color of the adhesive plastic that I have tried. It is quite easy to cut stencils or stickers. I often use it for cutting custom drilling and cutting templates for other projects. If you want to know how to use photoshop to create stencils from pictures stencil revolution has a good tutorial.

I did some experimentation with masking off parts of a steel plate with laser cut stencils and then I created rust by using Hydrochloric acid and Hydrogen peroxide. It worked pretty well however I need to work some more on the proportions between the Hydrochloric acid and the Hydrogen peroxide to get a nice rust coating on the unmasked metall. A word of caution, do NOT do this inside. I did and now I have a nice rust coat on every un protected piece of metal in my lab. Also wear gloves and eye protection. If you want more details about on the method I used to create these look in the comments for the video.

Art Foam/EVA foam

I have not done much cutting in EVA foam, mainly because I have not had any use for it. But if you are building small models and need laser cut parts this laser will get the job done for you.

Wood

Wood can be burnt but not cut. So if you are the woodworking type you might have a use for it. Sometimes I have seen that the laser does not start to burn instantly and that it takes a darker part of wood for the laser to get started, once it has started to smoke it goes on burning from that point.

ABS Plastic

When it comes to hard plastics like ABS it can melt the surface but not burn through. So just like it is with wood it is possible to engrave on ABS. The picture shows a quick test and is not the most beautiful thing I have done but it gives you an idea what to expect.

Hardware

If you are still interested in the hardware here is a quick rundown of the parts.

Mechanical

The whole frame is made from wood and the sliding tray slides on drawer sliders. Both x and y-axis are propelled by an M6 threaded rod.

The coupling between the frame and threaded rod consists of a M6 extension nut that I have incased in Polymorph plastic, Polymorph plastic softens enough to be molded by hand if you put it into boiling water and after it cools down it feels as hard as vinyl, very handy for motor mounts and this type of applications.

Motors

Both motors are NEMA17 stepper motors, 200 steps per revolution.

Laser

The laser is a MITSUBISHI/658nm-660nm 300-400mw CW Red Laser Diode/LPC-826 that I bought from eBay. It is mounted in a standard 5.6mm Laser Diode housing with a round heat sink. It is powered by a LM2596S based power module with built in current limitation. This way you will not risk feeding the laser to much power.

The LCP-826 diode should be run at an operation current <400mA and operation voltage <2.2V. To achieve this I started by connecting the 12V I use to drive the stepper motors to the IN on the DC-DC step down module. Then I connected a multimeter in Voltage measuring mode to the output on the board and adjusted the potentiometer closest to the input terminal on the card until I had 2.2V on the output. After I hade the desired voltage I changed the multimeter setting to Ampere measuring mode, remember to move the cable, and then adjusted the potentiometer closest to the output until I had a current output of 400mA. The middle potentiometer controls one of the diodes on the charger circuit and you can adjust it to set at what current the diod should light up.

LM2596S DC-DC Step-Down power supply. Picture made by coachlam.

The laser is turned on and off from the spindel on/off pin of the Arduino nano. Spindel on/off is connected to an Logic level Mosfet which enables me to control a 12V signal from the Arduino.

Remember that you should always wear laser eye protection when using this kind of lasers. When I started to build this laser cutter I decided to buy a pair of laser protection glasses. After doing some reading I decided on a pair from dragonlasers.com called LSG08. The LSG08 are designed to block light at the frequency 190-450nm and 598-752nm which covers this laser. I am no expert but from what I found after some reading I wanted a pair that was OD5-6 certified. OD stands for optical density and each step on the scale is a factor of ten. So OD1 will reduce the amount of light of a specific frequency by 10, OD2 would reduce it by 100 etc. Here is a diagram of the LSG08 light blocking properties.

LSG08 OD diagram

I am not saying that the really cheap glasses that you can buy of e-bay for around won’t work but I didn’t want to take that chance. The ones I got from dragon lasers does seem to work very well since I can still see! What is important is that the laser protection glasses are designed to block the frequency of your laser. If you are using a infrared laser then this is extremely important since the light is not visible to the naked eye.

Electronics

The stepper motors are controlled by two Easy driver stepper motor drivers. The Easy drivers are connected to an Arduino nano which is running grbl 0.8. They are connected as described on the grbl wiki page. Power to the laser is turned on and off using a logic level mosfet.

Limit switches

I have connected two micro switches to both sides of the x-y table, the limit switches as they are called serve two purposes.

1. Stop all movement if the end of the x-y table is reached.

2. Serve as indicators for the homing sequence.

The homing sequence is used when starting up the cutter to find the starting point every time you start. When you initiate the homing sequence the machine will run both motors until both switches in the negative directions are triggered. Then the motors will reverse direction and run slowly until the switch is released and that is the starting point. The homing sequence is initiated by sending the command $H to the controller and most G-code sender applications has a button to initiate the homing sequence.

One very very important thing to have in mind when using grbl as a base for a laser engraver is that you have no z-axis. However the homing mechanism used in grbl expects the limit switches for all three axis to trigger, there for you have to wire a pushbutton to serve as your z-axis during the homing sequence. If you don’t have the faked z-axis limit switch, which you manually push, the homing sequence will never finish. An option to get around this would be to wire one of the x or y axis limit switches to the z-axis pin so that it serves as switch for both.

The limit switches are simple normally open micro switches that you wire from ground to pin 9 (x), 10 (y) and 11 (z) on the Arduino.

Software

For software I use UniversalGcodeSender-v1.0.6 to send the gcode to the Arduino that has been loaded with grbl 0.8. To create the gcode from an image I use Inkscape together with the LaserEngraver plugin. The whole procedure is very well documented in this instructable written by Groover.

Hey very nice writeup. Before I had built my own 300mW powered laser cutter I always wanted to know what it actually can cut/engrave. Actually wanted to create a similar writeup as you did here so wonderfully, so thank you for this 🙂 !

You know, your ”frankengraver” was studied in detail before I started to build mine so I guess that you should also have credit as well as groover for his instructable. So thank you for showing your build and inspiring me. I actually went though two old inkjet printers and a scanner in the hunt for good stepper motors before I just decided to take the cost for buying new ones. HP has started to use normal DC motors and then have a translucent strip with black marks on that is read by a photosensor to determine position.

I bought the ones from dragonlasers that I mention in the hardware part of the blog post. They seem to work fine. I’m not really an expert on laser protection glasses so what is in the post is what I know.

Hey.
Thanks for your fast reply., I really appreciate it. I just ordered the laser parts, it will take few weeks to them arrive to here. But when I get my cutter ready, would you like to see some pictures?

I basically have the frame and the electronics allready done, just the laser missing. But the problem I am having is that when I try to print a test file I made with incsape, it prints it so darn small! What could be causing this?

What kind of power supply are you using with the steppers? I am using a 12V 1A wall adaptor, and the steppers are making really weird noises sometimes

Perhaps you have set the wrong number of steps for your stepper motors in the grbl config file. If you are using motors with 200 steps per revolution with easy driver stepper motor drivers the easy drivers supports something called micro stepping which makes divides every step into 8 micro steps. If you have it setup like this so you should set the grbl config as if your motors had 1600 steps per revolution. The stepper motors do have a peculiar sound sometimes like they groan but that is perfectly normal.

Hey!
Could you please link me, what laser housing did you use?
I got the laser parts today, and did my best trying to focus the laser. I did not get the laser to burn, it didn’t make a paper even hot! I thought that the problem was in my multimeter, and I increasend the voltage. Eventually I ended up frying the laser module.

Also, how didi you messure the current? Did you put the laser module in series with the multimeter, or what?

If you are going to test the laser I would recommend using some kind of plastic, like electrical tape rather then paper. Also use a dark color but preferably not red since that will reflect almost all laser light since it’s the same color as the laser. The only paper I can cut is thin black paper.

To measure the current you put the multimeter in series with the laser. I run my laser at around 2.4V. I haven’t measured how much current it actually draws so I can’t tell you that. I have set the current limiter on the laser power supply to 400mA and that is not kicking in so I know it’s using less then 400mA at least.

The seller I linked to usually has the 660nm in stock, I would send him a message and ask if he will get them back in stock soon. I don’t know if the 650nm will work just as well, perhaps you could ask the seller that to. Based on what he is selling he should know.

I didn’t give it much thought at the time I was building, I made it a height where I could easily work with the material I wanted to cut without the laser being in the way. Stability wise I wouldn’t say that the height the laser is at currently is a problem, the frame is quite rigid and the forces involved are quite limited. However I might have gotten more ”cutting power” if the laser was closer to the material that is being cut given that it could be focused.

LM2596S DC-DC Step-Down power supply – I seem to be having a providing the laser enough current. I have tried a 12 and 18 volt stepped power supply (leftover from dead laptop). I can get the voltage to the correct level < 3v, but cannot seem to get the current more than 260mA. The laser diode says <340mA. While it lights, it will not burn. I get the same result with or without the laser diode in the circuit. Is there a problem using stepped power supplies with this?

As I understand it the amount of current the laser diode will use is in direct relation to the voltage. If you keep the voltage to under 3V then your laser will only use 260 mA, if you increase the voltage the laser will draw more current but it will also burn out very quickly. I think my laser uses around 250 mA as well, I fried one other laser diode with to high voltage when I tried to get the current up just like you so be careful. My laser burns well with just 250 mA so I would rather suspect your optics then the diode it self. What optics are you using? Have you tried to focus the laser? I used a peice of black plastic when focusing the beam since it was easy to see when it started to smoke.

I haven’t tried to cut overheads yet. If I just look at the laser in the video it looks very similar to mine, just judging from the light intensity. I am certain that you will have to color it black as is done in the video though, otherwise the beam will go right through without affecting it. I will try to remember to pickup some overhead transparencies next time I’m at the store and let you know.

Test GRBL file? I was wondering if you know of a test file I could upload to my laser cutter? I tried to create code base on imported images, but had poor results. Maybe some lines at know distances apart + length (horizontal, vertical, diagonal) and a couple of circles. I found I had to slow down the stepper speed to keep from skipping steps. I made the laser head swappable so I can replace it with a Z-axis and dremmel tool. Found a good use for an old CPU heat sink:

Hi, of course I can send you a gcode file I know works. Send me an e-mail at jenslabs@gmail.com.

Can you specify a little bit more what kind of problems you are having with the gcode files you create. I have had problems where the laserengraver plugin adds a blank line in the beginning of the gcode file which has to be removed before the gcode sender can use the file.

I was all set, and burned another laser diode, while trying to focus it. Arrgh!
How did you get the beam into focus? I am using the same housing as you do, but the beam is still very wide. I can’t get the beam to a nice little spot as it should be..

I so sorry to hear that! Can you describe what you mean by ”burned” the laser. Did is stop working all together? If so have you made sure that the voltage isn’t to high, it should be around 2 volts. I didn’t do anything special when it comes to focusing the laser. After I had mounted the laser in it’s housing i used a flat screwdriver to rotate the laser lens into position. The metal ring that you are supposed to use when focusing was a bit loose and I could only use it for fine tuning. The method I used was very simple. Look at the dot and twist the ring until the dot is a tiny as possible.

I was wondering if you have tried anything with glass? Maybe if it was painted with a very light coat of flat black paint first it might work, thoughts? I was just trying to think of a way of pulling it off. I built a vey small machine just to play with, but will be making the guides and flat bed much larger very soon.

I have not tried to etch on glass. I suspect it will be difficult. You most definitely need to add some kind of coating of paint that the beam can focus on. I think that a best case scenario the paint might bind to the glass but more likely the laser will not effect the glass at all. I will give it a try next time I run the cutter. If you do any experimenting on your own I am very interested in your results. Good luck.

i have used a 1w blue laser to etch black glass from my welding mask. it doesnot melt the glass so much as superheat the dye in the glass and explode tiny fragments off the surface. it can do very fine work and fast.

I used flex couplers that I bought from ebay, e.g. http://ebay.to/1wgxwEc. They come different sizes so make sure you buy ones that fits your motor shaft size in one end and the threaded rod dimension in the other.

Could you upload a schematic of your electronics connections?
I’m interested in the connections of the mosfet with the LM2596 and the laser.
What resistor values did you use?
Did you use any high power resistor?
thank you,
John

Regarding the laser driver I do have a couple of questions (I bought a similar driver)

1) Voltage I adjusted to the required voltage
2) Current measurement is unclear to me since I do not want to fry my laser. Do you short the driver and measure the current flow? Or do you attach the meter with your laser diode?
3) You say you modulate on / off with a MOSFET. What kind? Do you put the mosfet on the laser output?
4) I have a TTL capable driver. I suppose I could turn the laser on and of using the Arduino pin?

I did as you say, just shorted the drivers outputs with the multimeter in current measuring mode. Then I adjusted it to what I thought was a good max current, nothing fancy. I used a logic level mosfet, I think it was an irl540, since I didn’t have a driver board that was prepared for input. I agree that you probably just need to connect the on off pin from the arduino to your driver.

Hi, sorry if someone might have already asked this question, this post is from 3 years ago… But can you use it to engrave pcb? Actually not directly laser on copper, but you can spray some thin black paint over the board, and then remove the paint using the laser, to etch the board later. Have you ever tried this? Please let me know if it works, I’m really interested in doing it.